Wednesday 9 May 2018

KEEP it Local- Dilemma in Reconstruction of Shelter-Post disaster

It's not the violent shaking of the ground itself that claims the most victims, but the collapse of poorly constructed buildings. The earthquake sequence destroyed 490,000 houses, mostly traditional mud-brick and mud-stone houses built and occupied by the rural poor.
" The largest single need identified in the PDNA was for “housing and human settlements”: 755,000 houses were destroyed or damaged. "
Central Bureau of Statistics of Nepal for 2014/2015 indicates 40.6% of houses in the country constructed are out of stone and wood. Many engineers focusing on earthquake safety strive to use local materials, however the Nepali case appeared bit different, the engineers learn modern construction materials and try to apply without much innovation on use of local materials, it was evident from the catalog of house designs distributed by DUDBC after the 2015 earthquake. 
However, we have used the local materials (stone and wood) in the permanent house reconstruction improving the flaws identified.

Foundation: The foundations of the stone houses were shallow less than 3 feet depth. The project proposed and adapted foundation at least of 3 feet depth with bonding to superstructure.
Corner walls: The stones used in corner walls were of not of regular shape, this was one the reasons of corner walls toppling leading the toppling of walls and the house. The project focused on strengthening corner walls by using good stones and tying with wooden vertical posts bonded with wooden horizontal bands.

Through stone: Through stone placed at the regular intervals in the walls act as a binder to wall, this was missing in the old stone houses. Project introduced use of through stones at regular intervals in the walls of the houses reconstructed.

Lack of bonding: The stone house walls were not bonded with combination of horizontal and vertical bands. The project introduced wooden horizontal and vertical bands. Plus, the window and door opening spacing was adjusted in compliance to the national building codes.

Gabble walls: Gable walls were of stone and not bonded with the walls and roofs, most of the houses toppled from gable walls. The project replaced stone gable walls with light material, corrugated galvanized iron sheet and for some houses wood tied to walls and roofs.

 Wood Treatment: In the rural context wood are painted and some times coated with lube oil ( mobil) to protect them from termites. Smoky kitchens used to be another protection of wood inside the house and natural seasoning (use of stack wood) were the practices. Proper treatment of wood was lacking.
Wood is a natural organic material and as such, can be degraded by biological organisms: bacteria, fungi (rot) and insects (woodworms and termites). Wood is also vulnerable to direct sun light and moisture, which affect its durability and increase the rotting process. Disodium Octaborate Tetrahydrate (Na2B8O13·4H2O) DOT . Boron-based compounds for wood treatment were developed in New Zealand and Australia in the 1930s and became commercialized in 1949. Over nearly 70 years borate mineral has been used worldwide proving its efficiency as wood treatment. 
DOT is a water-soluble solution that can easily penetrate dry and wet wood. It takes advantage of the moisture content in the wood to penetrate deeper. For fresh cut timber, where the moisture content can be 35% or higher by weight, the DOT solution penetrates timber logs more completely and faster. DOT is known to be an effective, eco-friendly and low-cost remedy for killing rot organisms and wood-destroying insects in infested wood and preventing its recurrence.
The project introduced the DOT for the wood treatment in its housing component. Boric Acid and Borax was prepared at sites of each house reconstruction following the standard mixes. The woods to be treated are dipped in the solution for diffusion effect. People used the local wood species of Chilaune, Salla, Uttis, Lapsi and Sal. One of the advantage of DoT wood treatment is that even fresh cut woods can be treated with moisture content of 30 to 40 percent and dried wood could be dipped in water for about and hour before immersing into Borax and Boric solution.
Use of local materials in reconstruction has created awareness among local people that the salvaged material can be used for reconstruction, this also reduces financial burden of house owners. (560 Individual Houses are built)

However, 2335 Households surveyed to identify the type of technical assistance need- in housing revealed the housing interest were of concrete not of stone and wood.

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